1. Field of the Invention
The present invention relates to a spray gun for paint and similar media which can be pressure fed, suction fed or gravity fed.
2. Description of the Prior Art
Spray guns for paint and similar media typically have a gravity feed, a suction feed or a pressure feed paint delivery system.
Gravity feed spray guns typically use a paint container on top of the spray gun, and the paint is fed by its own weight and atmospheric pressure, by gravity, into the spray gun. Gravity feed allows spraying of heavy materials, uses all of the material in the cup and is gaining wide popularity in automotive refinishing. Further, gravity feed requires less air pressure for operation than the suction or "siphon" feed method. The use of liners allows for simple cleaning of the device after use and provides for upside-down spraying. Gravity feed spray guns are disclosed in U.S. Pat. No. 5,727,736 entitled "Spray Applicator with Air Shut-Off Valve" issued on Mar. 17, 1998 to Tryon and U.S. Pat. No. 4,811,904 entitled "Spray Medium Inset for Spraying Pistols and a Spraying Pistol Suitable for Application of Such Insets" issued on Mar. 14, 1989 to Ihmels et al.
Suction feed spray guns use a suction created by a pressurized air source to draw the paint from a container up into the pressurized air stream. Suction feed typically allows larger quantities of paint to be used compared to gravity feed systems. Additionally, different paints or colors can be stored in different suction feed cups ready for use. Suction feed paint sprayers have achieved wide popularity among many end user segments. A suction feed spray gun is disclosed in U.S. Pat. No. 5,655,714 entitled "Pivotable Syphon Tube" and issued on Aug. 12, 1997 to Kieffer et al.
Pressure feed spray guns use a pressurized air line to the paint container to pressurize the paint and force it into the spray gun. Pressure feed allows spraying of extremely heavy materials, particularly when a large paint capacity is required, such as more than one quart. Pressure feed allows the spray gun to be held upside-down while spraying without the concern of leaks or drips. Moreover, a pressure feed spray gun is light because the paint supply can be separate from the spray gun.
Therefore, different paint applications and different users may choose different spray guns--gravity feed, suction feed or pressure feed. However, a single user may be reluctant to acquire spray guns of all three types. U.S. Pat. No. 4,760,962 entitled "Spray Gun Paint Cup and Lid Assembly" issued on Aug. 2, 1988 to Wheeler provides for the selection of pressure feed or suction feed but does not provide for gravity feed. Additionally, the configurations required for the two different feeds may not be intuitively obvious to a user. Similarly, U.S. Pat. No. 4,174,071 entitled "Spray Gun Assembly" issued on Nov. 13, 1979 to Lau et al. discloses a spray gun with an optionally pressurized paint supply. U.S. Pat. No. 5,069,389 entitled "Adapter for an Air Spray Gun" issued on Dec. 3, 1991 to Bitsakos provides a gravity feed attachment to a conventional spray gun. U.S. Pat. No. 5,582,350 entitled "Hand Held Paint Spray Gun with Top Mounted Paint Cup", issued on Dec. 10, 1996 to Kosmyna et al. discloses a hand held paint spray gun with a top mounted paint cup. The spray gun can operate as both a gravity and a suction feed.